Apparatus for expanding tubes

ABSTRACT

THIS INVENTION PROVIDES APPARATUS TO ASCERTAIN THAT THE SELECTED DEGREE OF INTERFERENCE FIT IS BEING PRODUCED AS EACH END PORTION OF EACH TUBE IS EXPANDED INTO ITS TUBEHOLE IN ITS MATING TUBE-SHEET. THE APPARATUS SENSES AND CHECKS THE WORK-PRODUCING FORCE AT SELECTED MOMENTS DURING EACH WORK CYCLE, AND IF ANY FORCE CHECKED IS NOT THE PROPER MAGNITUDE SAID APPARATUS INDICATES A DEFECTIVE WORK-CYCLE HAS BEEN PRODUCED.

W. E. STARY June 22, 1971 APPARATUS FOR EXPANDING TUBES 4 Sheets-Sheet 1Filed Jan. 27, 1969 INVENTOR June 22, 1971 APPARATUS FOR EXPANDING TUBESFiled Jan. 27, 1969 32 SOL LV W. E. STARY 4 Sheets-Sheet 2 PRVI INVENTORwr w June 1971 w. E. STARY 3,585,?M

APPARATUS FOR IXPANDENG TUBES Filed Jan. 2'7, 1969 4 ShOOiS-ShCCt 3PRESSURE PRESSURE EY D 1 ED m DM m g A g u) D (n g DV DD 3] a: l a: (1r1 INVENTOR United States Patent 3,585,701 APPARATUS FOR EXPANDING TUBESWalter E. Stary, P.0. Box 578, Levittown, Pa. 19058 Filed Jan. 27, 1969,Ser. No. 804,041 Int. Cl. 1323p /26 US. Cl. 29202 12 Claims ABSTRACT OFTHE DISCLOSURE This invention provides apparatus to ascertain that theselected degree of interference fit is being produced as each endportion of each tube is expanded into its tubehole in its matingtube-sheet. The apparatus senses and checks the work-producing force atselected moments during each work cycle, and if any force checked is notthe proper magnitude said apparatus indicates a defective work-cycle hasbeen produced.

This invention relates to improvements in apparatus for expanding theend portions of tubes. The apparatus powers and controls a roller-typetube-expanding tool as the tool enlarges a linear portion of a metaltube to bring the tube portion into tight engagement with a tubehole inwhich it is being assembled.

A principal use for this apparatus is to make pressuretight tube-jointsbetween tubes and tube-sheets in heatexchange apparatus. Heat-exchangeapparatus manufacturers make many such tube-joints each work day. Mostof this work involves expanding small tubes, l-inch O.D., or less. Thetube-sheets range from very large units, concontaining thousands oftube-holes, to small tube-sheets, containing about 30 tube-holes forA-inch O.D. tubes. The small units are usually quantity-production runsof many units, each with the same number and arrangement of tube-holes.

Automatic drilling equipment which locates the positions for holes andthen drills the tube-holes has become a competitive necessity. There isan identical need for similar automatic equipment to make thepressure-tight joints between tubes and tube-sheets. Parts made by theautomatic drilling machines can be visually and mechanically inspectedto make certain the holes being drilled are satisfactory and within theallowed tolerances. No such inspections can determine the quality, thetightness, of the tube-joints.

A principal objective of this invention is to provide improvements forthe apparatus for expanding tubes covered in my Patent No. 2,690,205,issued Sept. 28, 1954, which make said tube-expanding apparatusself-inspecting so that if and when said apparatus produces a defectivetube-joint, indicators are activated, the controls are made inoperative,and the action is stopped. The indicators tell which type of faultoccurred thus indicating the corrective actions needed. The controlsmust be manually reset to again make the apparatus operative. Thus thetubeexpanding apparatus, as improved by this invention, can workunattended and not do more than one cycle of defective work.

The subject tube-expanding apparatus is thus made usable in an automaticmachine which carries the apparatus and moves it over the face of atube-sheet, positioning the apparatus to get the axis of itstube-expanding tool 3,585,701 Patented June 22,, 1971 coincident withthe axis of the selected tube-hole, so that the tube-expanding apparatuscan be axially advanced to get its tube-expanding tool into the selectedtube-end so that said tube-end can be expanded. After the tube-expandingcycle is completed, the apparatus is retracted, withdrawing the toolfrom the expanded tubeend, so that a movement to the next programmedlocation can be made. Thus the automatic machine can continue to do workand expand tube-ends until the programmed work is completed, or untilone defective workcycle is made.

Other objects and advantages of the improvements which are parts of thisinvention will become apparent from the following description. Theaccompanying drawings illustrate these improvements.

Referring to the drawings:

FIG. 1 is a side elevation of a tool-driving apparatus with atube-expanding tool connected thereto. This figure is identical to FIG.10 in my above described Patent No. 2,690,205, except for the additionof a second annular row of balls in the thrust bearing of the tool.

FIG. 2 is a schematic diagram of a system of hydraulic elements whichmay be used to produce and control the axial movements of the mandrel ofthe FIG. 1 tool, and to monitor some of the tool actions to make certainthey are proper.

FIG. 3 is a schematic diagram of a system of electrical parts which maybe used to actuate and control the hydraulic elements in FIG. 2, and toproduce the indicating and work-stopping actions when any hydraulicelement in FIG. 2, which is monitoring said tool actions, indicates animproper tool action has occurred.

FIG. 4 is a side elevation of the FIG. 1 tool-driving apparatus, withits tube-expanding tool having angled rollslots. The FIG. 4 assemblyincludes diiferent frame plates which provide means for slidablyconnecting said apparatus to the carriage of an automatic positioningdevice so that said tool driver may become a part of an automaticmachine. An automatic tool lubricating device is also included.

FIG. 5 is a schematic diagram of a system of hydraulic elements whichmay be used to power and control the FIG. 4 tool-driving apparatus.

FIG. 6 is a schematic diagram of a system of electrical parts which maybe used to actuate and control the hydraulic elements in FIG. 5, and tooperate the toollubricating device shown in FIG. 4.

FIGS. 7, 8, 9, and 10, are graphs showing the relationship of thehydraulic fluid pressure relative to time, as various advance strokes ofthe tool-driving apparatus are made. They are included to illustratesome of the proper and improper hydraulic reactions which occur, or mayoccur. They are used for references in the descriptions of some of theimprovements brought forth in this invention.

FIG. 11 is the FIG. 9 in said Patent No. 2,690,205,

hereinbefore described. It is included for convenience in the referencespertaining to it in the discussions of some of the parts of thisinvention.

FIG. 12. illustrates one of the potential improper conditions which maybe encountered in automatically expanding the subject tube-ends whichwould cause defective work cycles.

FIG. 13 is a schematic diagram of a system of hydraulic elements whichmay be used to power and control the FIG. 1 tool-driving apparatus,including some 3 alternate hydraulic elements which may be used to getimproved tool action and additional means for monitoring the tool actionso as to check the quality of each tubejoint as it is made.

FIG. 14 is a schematic diagram of a system of electrical parts which maybe used to actuate and control the hydraulic elements in FIG. 13, withadditional means to monitor the tool action and to produce additionalindicating and work-stopping actions if said tool actions are notproper.

In the diagrams of hydraulic systems, all solenoid operated valves areschematically shown in their normal condition with solenoids notenergized. In the electrical diagrams, all switch contacts are shown intheir normal, not actuated, position.

The following notations and abbreviations will be used in thedescription and discussion of the apparatus.

R+ number prefix will identify contacts on a specific relay.

D-I- number prefix will identify contacts on a specific time-delay unit.Each time-delay unit has its contacts shift position the delay intervalafter coil is energized.

NO signifies normally open, and NC signifies normally closed, for allmanual, mechanical, and relay-operated switch contacts, and for switchcontacts in pressure sensitive devices.

SOL+ symbol indicates the solenoid on solenoid-operated valve having thesame symbol designation.

Referring to the drawings, particularly FIGS. 1, 2, and 3, ashereinbefore mentioned, FIG. 1 shows the FIG. 10 apparatus of saidPatent No. 2,690,205. The FIG. 1 apparatus has its tube-expanding toolin position to expand the end of tube 1, into a tube-hole in tube-sheet2. Rollcage 3, containing several tapered rolls 4, has tapered mandrel 5centrally located in the cage and rolls assembly, with mandrel 5 in itsretracted position.

The combination depth-control gage and thrust-bearing housing 6 containstwo annular rows of balls 7, one row on each side of the thrust-flangeportion of roll-cage 3, backup ring 8, and retaining ring 9, thusforming an assembly which keeps roll-cage 3 supported, axiallypositionable, and free to rotate. Connector 10 connects the roll-cageportion of the tool assembly in a fixed axial position relative to theframe of the tool driver. The frame consists of front plate 11, rearplate 12, and four tie-rods, tie-rods 13 and 16 being shown, andtie-rods 14 and 15 being positioned at the rear corners of thetrapezoidshaped frame plates 11 and 12, directly behind rods 13 and 16in the subject view.

The axial forces which produce the tool actions are provided byhydraulic cylinder 17 attached to rear frame plate 12. Advancing andretracting movements of mandrel 5 are produced by hydraulic fluidentering the proper end of cylinder 17 and moving piston 20. Piston rod21 connects to mandrel power-rotating unit 18, thus causingpower-rotating unit 18 to move axially as piston 20 moves. Shaft 19, ofpower-rotating unit 18, passes thru front frame plate 11 and connects tomandrel 5 so mandrel 5 must rotate with shaft 19, of power-rotating unit18, and reciprocate with piston 20.

Lug 22, a part of the housing of power-rotating unit 18, is slidablyfitted between tie-rods 16 and 15, rod 15 being on the other side of lug22, in back of rod 16. Thus the torque reaction produced when the tooldoes work is transmitted to the tool-driver frame.

The following description of the expanding of a tubejoint to apreselected tightness refers to FIG. 1 apparatus axially powered by theFIG. 2 hydraulic system as controlled by the FIG. 3 electrical system.The apparatus is in its regular operating condition, as it is at the endof a normal work cycle of tube-expanding. Power-rotating unit 18 isrunning, and mandrel 5 is axially retracted and rotating. The output ofhydraulic pump P1 is flowing thru tu'be T1, thru pressure-relief valvePRV, and back to tank 25. The hydraulic system maximum pressure, asestablished by valve PRV, exists in tubes T1 and T2, and in cylinder 17where it acts to hold piston 20 in its retracted position.

The electrical .system is operable with cycle-control switch S1 in itsnormal, NC, position. The coil of relay R1 is energized and NO contactR11 is closed. The coil of time-delay unit D1 is being maintainedenergized by closed NO contact D11, and NC contact D1-2 is held open.The coil of relay R2 is not energized and NC contact RZ-l is closed.Measuring cylinder MC is retracted and NO contact MB, in switch MB, isclosed. Thus SOL B, on normally-closed hydraulic valve B, is energizedand valve B is open.

A work cycle is started by operating switch S1, in the following manner.Switch S1 is operated to open NC contact S1 and coil of relay R1 isdeenergized, thus opening NO contact R11 and stopping flow of electricalcurrent in line L1 beyond said contact R11. Coil of timedelay unit D1 isdeenergized and its switch contacts re turn to their not-energizedcondition with contact D1-2 closed. As switch S1 is released, relay R1is energized and contact R11 is closed. SOL A is energized shiftingvalve A so it directs hydraulc flow from tube T1 thru tubes T6 and T5,thru valve B which is being held open, thru tube T3 and to hydrauliccylinder 17 to put pressure behind piston 20, forcing piston 20, andmandrel 5, to advance.

Rolls 4 move radially outward as mandrel 5 advances, and when the rollscome into contact with the inner surface of tube 1, said rolls starttheir planetary rotating about said rotating mandrel 5. Said mandrelcontinues advancing, moving rolls 4 outward radially, expanding anddistorting the tube portion until the FIG. 11 condition is developed.The tube-sheet metal surrounding the tube-hole provides resistance tothe further radially out ward movement of said rolls and the hydraulicpressure increases and operates pressure-sensitive switch PX.

As NO contact P5 closes, the coil of relay R2 is energized, opening NCcontact R2-1 to deenergize SOL B allowing valve B to close. NO contactR2r-2 closes and SOL M is energized shifting valve M so it directs thehydraulic flow thru tube T8, thru the orifice of flow-control unit FC,and into measuring cylinder MC, to thus advance the piston of saidcylinder MC. NO contact R2-3 closes to hold relay R2 energized.

As soon as piston of cylinder MC starts to rise, arm 26, attached to thepiston rod of cylinder MC, allows the NO contact MB, in switch MB, toopen. Cap 27, threadably attached to said piston rod of cylinder MC,also rises as said piston rises. The fluid being discharged fromcylinder MC, as its piston rises, is forced into tube T4, Since valve Bis closed, said fluid is forced to flow thru tube T3 and into cylinder17, to advance piston 20 and mandrel 5. The piston of cylinder MCcontinues to rise, carrying cap 27 toward switch MT, until it operatesswitch MT, closing the N 0 contact MT. The support for switch MT, notshown, physically stops the further advance of said piston of cylinderMC, thus stopping the flow of fluid into cylinder 17, and thus stoppingthe axial advancing of mandrel 5.

As the NO contact MT, in switch MT, closes, the coil of time-delay unitD1 is energized. After the selected timedelay, NO contact D1-1 closes,and NC contact D12 opens. Closed contact D1-1 maintains time-delay D1 inits energized condition. As contact D12 opens, SOL A, of valve A, andcoil of relay R2, are deenergized. Valve A shifts to direct hydraulicflow to tube T2. At this same moment relay R2 is being deenergized andits contact R2-2 opens and deenergizes SOL M, thus permitting valve M toshift to connect tube T8 to tank 25, and to connect tube T5 to tube T6,and NC contact R2-1 closes. The hydraulic flow thru tube T2 goes tocylinder 17 forcing piston 20 to retract, thus retracting mandrel 5. Thefluid, in cylinder 17 on the other side of piston 20, is forced intotube T3. Since valve B is closed, the fluid being discharged fromcylinder 17 must flow through tube T4, into cylinder MC, to force the MCpiston to retract. The exhaust flow from cylinder MC flows thru thecheck valve in flow-control FC, thru tube T8, and into tank 25.

As the piston of cylinder MC is being retracted, arm 26, connected tosaid piston, is moving toward switch MB. Said arm 26 operates switch MBjust before cylinder MC becomes fully retracted, and the NO contact MB,in switch MB, is closed. Since NC contact R2-1 is already closed, SOL Bis immediately energized and valve B is forced to open. The remainder ofthe fluid to be discharged from cylinder 17 can then flow thru tubes Tand T6, and on to tank 25. When piston 20, in cylinder 17, is fullyretracted, the work cycle is completed and the apparatus is ready foranother cycle of tube-expanding.

The preceding description of the operation and actions of FIGS. 1, 2,and 3, ignores pressure-sensitive units PL and PH, of FIG. 2, andtime-delay units D2 and D3, relays R3, R4, and R5, and recording andindicating units X and Y, of FIG. 3. These additional parts of theapparatus are elements added by this invention. The followingdescription of the actions of these additional elements of hydraulic andelectrical apparatus will refer to FIGS. 7, 8, 9, 11, and 12, as well asthe basic references FIGS. 1, 2, and 3.

FIG. 11 exaggerates the distortion of tube 1 in its tubehole 2H, forpurposes of illustration. The usual practice is to have a minimumpractical clearance between tubes and tube-holes so that thepressure-tight joints can be produced, in minimum time, and with minimumthinning of the tube wall to thus develop the maximum tube-jointstrength.

FIGS. 7, 8, and 9, chart the hydraulic pressure in tube T3 relative totime during an advance stroke of piston 20 and its associated mandrel 5.

Curve A, FIG. 7, charts the pressure for an advance stroke with no tubeportion restricting the radially-outward movement of rolls 4. Allpressure recordings are taken in tube T3, near where pressure-sensitiveunits PX, PL, and PH, connect to tube T3. Thus the pressure recorded incurve A, FIG. 7, is the pressure required to produce the axial advanceof the apparatus plus the pressure required to produce the flow thru thesystem, beyond the recorder connection point in tube T3, as mandrelfreely advances at the velocity produced by the output-volume of pumpP1. In curve A, the pressure quickly rises as advance movement starts,then it remains substantially constant until piston 20 reaches itsforward-travel limit, then the pressure immediately rises to the maximumpressure available in the system, as controlled by relief valve PRV.

Curve B, FIG. 7, charts the pressure required to get the samefull-length advance stroke with a tube portion 1, on the tool, but withno tube-hole 2H surrounding said tube portion, thus indicating the forcerequired to get the maximum expansion and distortion of the tube portionproducible by the tool being used. Obviously, the tube-hole must besmaller than this maximum diameter. Curve B starts, and continues,exactly the same as Curve A, until point B1 is reached. At point B1,mandrel 5 has advanced and rolls 4 have moved radially outward tocontact tube 1, and the planetary rotation of rolls 4 and cage 3 starts.The pressure rises relatively rapidly for the initial portion of thetube-expansion and distortion, and then the pressure-rise changes to amore gradual rate of increase until the end of the advance stroke. Aspiston 20 reaches its forward-travel limit, the pressure increases tothe system maximum as it did in Curve A. Thus Curve B starts and endsexactly the same as Curve A. The portion of Curve B which differs fromCurve A is the portion of the advance stroke in which Work is being doneon tube portion 1.

Curve C, FIG. 8, charts the pressure when the advance stroke expandstube portion 1 into pressure tight engagement in its tube-hole 2H, intube-sheet 2. The tube portion is the same (size, metal, and length) asthe tube portion charted in curve B, FIG. 7. The pressure-peak CX is thepressure developed at the moment the hydraulic apparatus responds to theclosing of NO switch contact PX, in pressure-sensitive unit PX. Saidaction occurs as the FIG. 11 condition is developed, as describedhereinbefore, in connection with the description of FIGS. 1, 2, and 3.

As valves M and B are shifting, and as cylinder MC is starting andaccelerating to its selected piston-advance velocity, there is a shorttime interval during which no fluid is added to cylinder 17, and a shorttime interval while the fluid flow-rate is accelerating to its fullvelocity. The mandrel continues to rotate, during these short timeintervals, but mandrel does not advance, and the rolls continue to rolland thin the tube-wall. The resultant reaction is a decrease in thepressure in tube T3. Then the mandrel resumes its advancing, and as thetube portion becomes in its tube-hole, the resistance to furtheradvancing of the mandrel is increasing, and the pressure is increasing.The second pressure peak CM, in curve C, occurs at the momen the pistonin cylinder MC stops advancing. During the dwell period which follows,while time-delay unit D1 is timing out, the mandrel continues to rotatebut not advance, the tube-wall is additionally thinned and the pressureis decreasing. The pressure at the moment the apparatus responds to theopening of NC contact D12 is indicated by point CD, FIG. 8.

Various faulty conditions can exist which permit the making of anautomatic work cycle with the tube-joint not properly expanded. One suchfaulty condition is illustrated in FIG. 12, where one roll 4 has fallenout of its roll-slot. Rolls are normally contained in their roll-slotsby one of two methods, a retaining device such as spring 42, illustratedin FIG. 4, of my Patent No. 3,016,944, or by caging lips L, illustratedin FIG. 6, of my Patent No. 2,772,716. The retaining device can break,the caging lips wear out, and in either case the roll may then fall outof its slot when tool is withdrawn from a tube end.

Curve D, FIG. 9, charts the pressure as it might be when the advancestroke expands a tube-end with the faulty tool of FIG. 12. The tubeportion, and the tubehole, for curve D, are identical to those used inmaking curve C, FIG. 8. The pressure peak DX will be substantially thesame magnitude as peak CX, but the pressure reaction thereafter will bedifferent. Note valley DV is considerably lower than valley CV, and peakDM is much lower than peak CM. It is obvious the FIG. 12 tube can not beproperly expanded. An unattended automatic machine could continue tomake such faulty work cycles.

This invention provides means to stop the apparatus as soon as it hasmade one, above described, faulty Work cycle, in the following manner.

As hereinbefore described, the pressure peak CX, FIG. 8, occurs as thetube portion is being expanded, just after pressure-sensitive unit PXand relay R2 are operated. Time-delay unit D2, FIG. 3, operates to startits timedelay interval at the same moment relay R2 is energized. The NOcontacts D21 and D2-2, close at the end of the D2 time-delay interval.Said D2 time-delay interval is selected to close said D2 contacts atabout the bottom of the valley CV, FIG. 8. Contact D2-2 closes andenergizes the coil of time-delay unit D3. Time-delay unit D3 is set tooperate its contacts after a short delay. Thus NC contact D31 opens soonafter contact D2-1 is closed. Pressure-sensitive unit PL is set tooperate at the pressure developed at the bottom of valley CV, FIG. 3.Thus, if a pressure equal to, or greater than, the selected minimum CVpressure exists in the system, so that NO contact PL, onpressure-sensitive unit PL, is closed, at any time after contact D21 isclosed and before D3-1 opens, relay R3 will be energized. As relay R3 isenergized, its NO contact R3-1 closes and holds relay R3 energized, andNC contact R32 opens and is held open. Then, when timedelay unit D3times out and closes its NO contact D3-2, relay R5 cannot be energizedbecause said contact R3-2 is open. Thus the work cycle is an approvedwork cycle in that the minimum pressure after the CX, FIG. 8,pressure-peak was adequate.

If the pressure is too low so that NO contact PL, on pressure-sensitiveunit PL, is not closed during said time interval after contact D2.1closes and before D3-1 opens, relay R3 Will not be energized and its NCcontact R3-2 will remain closed. Then, when time-delay unit D3 times outand closes its NO contact D32, relay R5 will be energized, thus closingits NO contact R5-2 to hold relay R5 energized, and its NC contact R51Will be held open, thus making the electrical system inoperable untilswitch S2 is operated. The elements associated with relay R5 act to stopthe automatic action of the apparatus when a toolow pressure exists,during the selected short time interval, after pressure-sensitive unitPX is operated.

As relay R5 operates to close contact R5-2, indicator Y is energized togive the selected indications that machine has stopped because relay R5is energized, thus indicating that the pressure was too low after the CXpeak, during the previous work cycle.

Some faulty actions can produce a pressure which is higher than thenormal pressure developed at peak CX, or peak CM, FIG. 8, whichever isthe highest for the correct actions for a particular set of workingconditions.

If a too-high pressure is developed at any time during a work cycle,pressure sensitive unit PH, FIG. 2, which is set to operate at apressure slightly higher than the normal maximum pressure, is actuated,thus closing NO contact PH, FIG. 3, and coil of relay R4 is energized.As relay R4 operates, NO contact R42 closes to hold relay R4 energized,and NC contact R41 opens and stops the tubeexpanding action. Contact R42remains closed, holding relay R4 energized, until reset switch S2 isoperated. The X indicator is operated and held operated by closedcontact R42. Difference in pitch of bells, or color of lights, gives aquick indication telling why the apparatus stopped, that is, whether itwas a too-high pressure, or a too-low pressure, which stopped theapparatus from making automatic work cycles. Proper corrective actionsshould be taken before switch S2 is operated to reset the controlsystem.

FIGS. 4, 5, and 6, disclose some other features of this invention whichprovide means for incorporating the tubeexpanding apparatus into anautomatic machine which traverses a tube-field, advances and retractsthe tubeexpanding apparatus to get its tool into each tube-end, andexpands said tube-ends, as detailed in the following description.

In FIG. 4, frame members 41 and 42 contain guide bearings 43 and two ormore rod-ways 37, with said parts Frame members 35 and 36 are elementsof a carriage, not shown, of the positioning device, not shown, whichprovides means for moving said carriage in two normal directions so asto position the tube-expanding tool, attached to said apparatus, withits axis coincident with the axis of the tube to be expanded, so thatsaid positioning device can then axially advance the tool drivingapparatus to get its tool positioned in said tube to be expanded.

Roll-cage 33 has its roll-slots angled as shown so that when a tubeportion is being expanded and the tool planetary action starts, rolls 4tend to follow a spiral path forcing roll-cage 33 to follow said spiralpath in such a manner that said roll-cage tends to advance into thetube. Since tool depth-gage 6 is in contact with the outer face oftube-sheet 32, preventing said tool from traveling inward into thetube-hole, and since said tube is loose in said tube-hole, said tube ispulled toward the face of depth-gage 6, until it comes into firm contactwith said depth gage. Thus, if a tube is not in its proper axialposition, it will be pulled into said desired axial position as thetube-expanding operation starts. Obviously, if the tube is projectingoutward beyond the face of the tube-sheet,

it will be pushed into position as the tool enters said tube and itstube-hole, when the face of depth-gage 6 contacts the end of said tubeduring its travel movement as it enters said tube. Thus the tubes areproperly positioned relative to the face of the tube-sheet.

Solenoid-operated valve LV, nozzle 38, and hose 39, are parts of thetool lubricating device. Hose 39 can conduct a compressed gas containingatomized particles of a lubricant, and nozzle 38 can be positioned andshaped so that, when valve LV is opened, said lubricant is sprayed ontothe roll-containing portion of roll-cage 33. A prin cipal reason forlubricating the tool is to keep it clean and prevent a buildup ofparticles of scale on the rolls and mandrel of said tool. Said particlesof scale are worked loose from the inner surface of the tube, by therolling action of the tool, and they tend to become bonded to thesurface of rolls and mandrel, by the extremely high pressure existingbetween contacting portions of the surface of said rolls and mandrel,when the rolling action carries the particles into said areas ofhigh-pressure contact. The coating, thus bonded to surface of rolls andmandrel, provides additional resistance to the axial sliding of themandrel, relative to the rolls, thus reducing the effective forceadvancing the mandrel.

The tube-expanding actions of the FIG. 4 apparatus may be axiallypowered by the FIG. 5 hydraulic system as controlled by the FIG. 6electrical system, in the following manner. The systems are operable andin condition for an automatic-cycle start, with pump P11 running,hydraulic fluid flowing thru pressure-relief valve PRVl, back to tank25A, the system pressure existing in tubes T12 and T19, passing thrunormally-open valve C, and acting to hold piston 20, of cylinder 17, andits as-- sociated mandrel 5, retracted. The power-rotating unit 18, itsshaft 19, and its associated mandrel 5, are rotating. Tubes T13, T15,and T18, are connected to tank return line T17. Measuring cylinder MCIis retracted, and arm 26A is holding NO contact MB1, in switch MB1,closed, and normally-closed solenoid-operated valve B1 is open.

Control switch S3, FIG. 6, is operated to open its NC switch contact.The coil of relay R11 deenergized and NO contact R11-1 is open. RelayR21 is deenergized and its NC contact R21-1 is closed. As describedabove, NO contact MB1, in switch MB1, is being held closed, and SOL B1is energized and holding valve B1 open.

The positioning device is at a work position and it makes anaxial-advance movement to get the tube-expanding tool into the tube-end.Frame members 41 and 42 axially slide on ways 37, advancing thetool-driver apparatus until depth-gage 6 contacts the face of tube-sheet32. As said depth gage contacts the tube-sheet, switch S3 is operated tolet its NC contact close, thus energizing the coil of relay R11, closingNo contact R11-1. Time-delay unit D11 is not energized, and its NCcontact D11-2 is closed. SOL A1 is energized and valve A shifts todirect the hydraulic flow from tube T11 to tube T16, thru valve M1 andtube T15, thru valve B1 and tube T13, and On to cylinder 17 to advancepiston 20 and mandrel 5.

As mandrel 5 is advancing, the hydraulic fluid being exhausted fromcylinder 17 flows thru tube T19, thru normally-open valve C, thru tubeT12 and back to tank 25A. The mandrel continues advancing, and when theFIG. 11 condition is developed pressure-sensitive unit PXl is actuated,closing its NO switch contact PXl, the coil of relay R21 is energized,and the following actions occur. NC contact R21-1 opens and SOL B1 isdeenergized, allowing valve B to close. NO contact R21-2 closes andenergizes SOL M1 and SOL C of valves M1 and C respectively. NO contactR21-3 closes and holds relay R21 energized. The mandrel starts to makethe additional, measured-advance, portion of its axial advance.

As hereinbefore described, rolls 4 are caged in the angled roll-slots inroll-cage 33, so as to produce the tubepulling action. Said angledroll-slots also produce a selffeeding effect, advancing the toolmandrel. This selffeeding effect is referred to in my Patent No.3,016,944, wherein reference is made to Brackett, Patent No. 2,448,512.A prime objective of this invention is to make a tube-joint in minimumtime, thus making a maximum number of tube-joints per minute. It isnecessary to complete the tube-pulling action before the FIG. 11condition is established and the tube outer surface is in firm contactwith its tube-hole. It may, therefore, be necessary to angle rolls 4more than said rolls would be angled to get the normal, mandrel,self-feeding effect. Then, when the FIG. 11 condition is established,the mandrel may be pulled forward too rapidly so as to seriouslyoverload the apparatus or the tool. Or a normal self-feeding angle maycause the rolls to pull the mandrel forward faster than the desiredmandrel-advance rate, to produce the proper tube-wall thinning action,during said measured-advance portion of the cycle.

This invention includes means to stop the self-feeding action as theFIG. 11 condition develops and the tubejoint tightening action starts.Said means acts to hold back the mandrel with a holding-back force equalto, or greater than, the mandrel pulling force produced by theself-feeding effect of the angled rolls. As hereinbefore described, whenthe FIG. 11 condition is developed, pressure sensitive unit PX1 isactuated, normally-closed valve B1 is allowed to close, normally-openvalve C is closed, and valve M1 shifts to direct the hydraulic flow thrutube T18 to get an advance action of cylinder MC1. When valve C closes,the exhaust flow from cylinder 17 must flow thru counterbalance valveFP, to get from tube T19 to tube T12 and on to tank 25A. Saidcounterbalance valve FF is set to open at a pressure which gives aholding-back force acting on piston 20 equal to, or greater than, theforce needed to stop the mandrel-advancing action produced by angledrolls 4.

Curve E, FIG. 10, charts the pressure for a representativemandrel-advance action when a tube portion is being expanded with theFIG. 4 apparatus. Curve E, from the beginning of the mandrel avanceuntil pressure peak EX is developed, is similar to the same part ofCurve C, FIG. 8. The pressure needed in tube T19, to stop the advancemovement of piston 20, produced by the self-feeding effect developed byangled rolls 4, may be of the magnitude represented by the dottedhorizontal line EF, FIG. 10. Obviously, it is necessary to develop apressure in tube T13 of a greater magnitude than said EF pressure to getany additional advancing movement of mandrel 5. The pressure producingthe additional mandrel-advance must rise to the EY magnitude to get thedesired rate of additional advance, and said pressure then rises to theEM magnitude at the end of said mandrel advance. Pressure then drops offto the ED magnitude at the end of the dwell interval.

When time-delay unit D11 times out and opens NC contact D11-2, SOL A1and coil of relay R21 are de energized, valves A1 and M1 shift to givethe normal measuring-cylinder retract and mandrel retract actions, SOL Cis deenergized allowing valve C to return to its normally-opencondition, and counterbalance valve FP becomes inactive in the circuit.

As soon as the mandrel retract action commences, the tool is free to bewithdrawn from the tube-end it has expanded, and another contact ontime-delay unit D11, not shown, can initiate the actions of thepositioning device so that the tool-driving apparatus retracts, slidingback on ways 37. As frame member 42 approaches its travel limit,relative to carriage member 36, switch 53 can be operated to close itsNO contact thus initiating the action of the tool lubricating device. Assaid NO contact on switch S3 closes, SOL LV is energized, andnormallyclosed valve LV, FIG. 4, is opened to allow flow of the atomizedlubricant from hose 39 to nozzle 38 so as to spray said lubricant onroll-cage 33 and rolls 4. At this same moment, the coil of time-delayunit DL is energized, and when time-delay DL times out its NC switchcontact DL is opened, thus deenergizing SOL LV, allowing valve LV toclose and stop the flow of said lubricant. The NC contact on switch S3opens as the above lubricating action starts, but this does not affectthe mandrel-retracting action, if mandrel is not completely retracted atthe moment switch S3 is operated.

Means associated with the NO contact of switch S3 or with time-delayunit DL, not shown, can be used to start actions of the positioningdevice to move its carriage and said tube-expanding apparatus to thenext programmed location so that another cycle of tube-expanding actioncan be made. As said carriage and tube-expanding apparatus arrive atsaid next programmed location, the positioning device initiates actionsto advance said tubeexpanding apparatus to get its tube-expanding toolinto the next tube-end to be expanded.

FIGS. 13 and 14 show alternate systems of hydraulic and electricalelements for powering and controlling the FIG. 1 apparatus. FIG. 13 hasa large-diameter piston rod in its measuring cylinder MC2 andpressure-relief valve PRV3 acting to limit the pressure when cylinderquality of the tube-joint being made. The actions of the FIGS. 13 and 14systems in powering, controlling, and MC2 acts. FIG. 14 has means forsensing the actuating o1 pressure-sensitive unit PX2 twice during anormal tubeexpanding cycle together with means whereby the second actingof said pressure-sensitive unit PX2 inspects the monitoring, the actionsof the FIG. 1 apparatus, as a tube portion is expanded, are as follows:

The action starts as described for the FIGS. 2 and 3 systems andcontinues until PX2 is actuated, closing its NO switch contacts PX21 andPX2-2, when the FIG. 11 condition is developed. Since measuring cylinderMC2 is retracted and switch MB2 is being held operated with its NCcontact MB2-2 open, the coil of relay R6 is not energized this firsttime PX2 acts. PX2-1, closing, energizes the coil of relay R22, thusstarting the MC2 measuringcylinder action, as the similar contact on PXdoes in the FIG. 3 system. As shown in the FIG. 8 graph, after the firstpressure peak CX, which occurs in response to the FIG. 11 conditionbeing developed, the pressure drops and then rises again as the measuredstroke is made, said pressure rising to the CM peak. The FIG. 14electrical system uses this pressure increase, after the FIG. 11condition is developed and the CX pressure peak is established, as ameans of determining a satisfactory tube-expanding action in thefollowing manner.

As the measured stroke starts and MC2 piston advances, switch MB2 isreleased and its NC contact MB2-2 is allowed to close. Then, as themeasured stroke is made, when the pressure rises to a magnitude equal tothe CX pressure, said pressure-sensitive device PX2 is again actuated.Relay R22 is being held energized by its contact R22-3 and the signalgiven by PX2-1 is ignored. Switch contact MB2-2 is now closed and asPX2-2 closes, the coil of relay R6 is energized. NO contact R6-1 closesand holds relay R6 energized. NC contact R62 opens and is held open. Asmeasuring cylinder MC2 reaches its advance limit and operates switchMT2, NO contacts MT2-1 and MT2-2 are closed. Contact MT2-1 initiates theaction of time-delay unit D12. Contact MT2-2 closes but there is noaction since NC contact R62 is being held open. Thus the tube-joint isinspected and found to be satisfactory.

Obviously, if the pressure does not increase to a magnitude sufficientto operate pressure-sensitive unit PX2 the second time, before switchMT2 is operated, relay R6 will not be energized, NC contact R6-2 willremain closed, and the coil of relay R7 will be energized when contactMT2-2 closes. Then, as NO contact R7-2 closes to hold relay R7energized, NC contact R7-1 opens and is held open, and the controlsystem is inoperative.

The recording and signaling means Z, similar to means X and Y of FIG. 3,can give the desired signal to tell 1 1 that the apparatus isinoperative because said second pressure peak was not produced duringthe last work cycle. Operating reset-switch S5 deenergizes the coil ofrelay R7 to permit the system to again be operative.

As described hereinbefore, measuring cylinder MC2, in FIG. 13, has alarge-diameter piston rod. This provides means for getting aproportionally longer stroke of said cylinder MC2 relative to the strokeof cylinder 17, FIG. 1, and its associated mandrel 5. Thus it ispossible to get a finer-degree of adjustment of the additional-advancemovement of mandrel 5, after the CX peak, FIG. 8. Said adjustments aremade by rotating the threadably attached cap 27B, on the MC2 piston rod,thus changing the working-stroke of said measuring-cylinder MC2. S id.finerdegree of adjustment is especially desirable when the actualaxial-advance of the mandrel, after the OK peak condition of FIG. 8, isnear the short-stroke end of the adjustment range, when said actualaxial advance of the mandrel is on the order of .OZO-inch.

As the diameter of the MC2 piston rod approaches th inside diameter ofthe cylinder, the potential magnitude of the pressure on the exhaustside, in proportion to the pressure on the other side of the MC2 piston,increases since this pressure-ratio is substantially the same as theratio of the net areas on the two sides of said piston. Thus, ifpressure-relief valve PRV3 is not acting to limit the pressure enteringcylinder MC2, the pressure in tube T24, and in cylinder 17, FIG. 1,could be much greater than the system pressure as controlled by PRV2.

The various applications for heat-exchange apparatus lead to a greatrange of requirements for the tube-expanding apparatus. Obviously, atube-joint satisfactorily pressure-tight for a small heat-exchange unitworking at a maximum temperature of about 200 degrees, Fahrenheit, witha pressure differential of 5 to 10 p.s.i. from one side of itstube-sheet to the other Side, would not be satisfactory in aheat-exchange unit Working at a temperature of 1400 F., with a pressuredifferential in excess of 5,000 p.s.i. cross its tube-sheet. Both ofthese examples are common production items. The low temperature, lowpressure,

FIG. 4. The grooves provide recesses into which tube metal is forcedduring the tube-expanding operation. Proper flow of metal into saidgrooves increases the strength and pressure-tightness of the tube-joint.Obviously, the mandrel advance, after the CX pressure peak, FIG. 8, isthe portion of the mandrel advance forcing the metal to flow into saidgrooves. Thus a considerably longer stroke of measuring cylinder MC isrequired when expanding tubes into grooved tube-holes than is needed toproperly expand a tube portion into a plain, not-grooved, tube-hole.

For all the above examples, the general configuration of the pressure totime curves are similar. The magnitude of the pressure will bedifferent, and, as described above, the time to get from the X to the Mpeaks, such as time from CX to CM, FIG. 8, will be substantially longerwhen expanding tubes into the tube-holes in tube-sheet 32, FIG. 4,wherein said holes have grooves 32G. For purposes of illustration, thetimes between the X and M peaks, in FIGS. 8, 9, and 10, aresubstantially proportional to the average time when expandingtube-portions into tube-holes containing said grooves 32G. The cycletime, and the pressure-magnitudes, will vary substantially with the workrequirements, but the general characteristics always apply, and themonitoring and inspection elements disclosed in this invention alwaysapply.

It is obvious that all the inspection devices shown in the several setsof hydraulic and electrical systems can be combined and used in oneapplication, and it is obvious that economics Will frequently dictatethe choice of which features should be included in a machine built for aspecific type of tube-expanding work.

It will be understood that, while the features of this invention aredescribed in terms of their applications in automatically operatedtube-expanding apparatus, the features of this invention apply equallyas well in manually-operated apparatus with which the operator movessaid apparatus to get its tube-expanding tool into a tubeend to beexpanded, and he then starts an automatic cycle of tube-expanding. It isobvious the operator may be any unskilled person, with no knowledge ofthe requirements for a satisfactory tube-joint. The monitoring. andinspecting means added by this invention, make the tube-expandingapparatus inoperable as soon as one faulty work cycle is made. Saidunskilled operator can then get skilled help to make the necessarycorrections so that he can proceed with the work.

It will also be understood that, while the features of this inventionare described in terms of hydraulic apparatus producing the axialmovements of the tubeexpanding-tool mandrel, the invention appliesequally as well with apparatus having mechanical means for producing themandrel advance movement, wherein a change in the power requirements forthe source providing said mechanical force actuates watt-meters, orother devices, sensing the amount of electrical energy demanded toproduce the actions, or wherein strain gages, or springpoweredforce-sensing devices, sense the changes in, or the minimum or maximumamounts of, said forces, so as to then actuate means giving thereactions and responses which have been herein described.

Thus, while the invention has been described with reference to theparticular devices illustrated, it will be appreciated that it is not solimited. It is rather of a scope commensurate with the scope of thesubjoined claims.

What I claim as my invention is:

1. An apparatus which powers and controls a rollertype tube-expandingtool as it expands a lineal portion of a tube to a preselected tightnessin its tube-hole, said tool having a plurality of angularly-spaced,rotatable, radially movable, expanding rolls caged in anaxiallypositionable, rotatable, roll-cage mounted about a tapered,axially movable, rotatable, mandrel, with said apparatus supporting saidroll-cage assembly and said tapered mandrel so that said mandrel isaxially movable relative to said roll-cage, said mandrel, whilerotating, being axially advanced by a measurable axial force withcooperating means to sense the increase in said axial force produced themoment several angularly spaced areas on the tube outer surface arebrought into firm contact with the defining wall of its tube-hole,whereupon said apparatus is thereafter controlled to produce apreselected, additional, axial advance of said rotating inandrel,whereby said tube portion is expanded to the preselected tightness inits tube-hole; wherein force-sensing means is provided for sensing themagnitude of said axial force producing said mandrel advance, for apreselected, short, time interval after said preselected, additional,axial advance of said mandrel starts, said forcesensing means beingactuatable by a force a preselected amount less than the magnitude ofsaid axial force produced the moment several angularly spaced areas onthe tube outer surface are brought into firm contact with the definingwall of the tube-hole, said means acting so that if said force-sensingmeans is not actuated the apparatus control system is made inoperable,and an indicator is actuated to thus indicate said force-sensing meanswas not actuated during said preselected, short, time-interval.

2. An apparatus which powers and controls a rollertype tube-expandingtool as it expands a lineal portion of a tube to a preselected tightnessin its tube-hole, said tool having a plurality of angularly-spaced,rotatable, radially movable, expanding rolls caged in anaxiallypositionable, rotatable, roll-cage mounted about a tapered,axially movable, rotatable, mandrel, with said apparatus supporting saidroll-cage assembly and said tapered mandrel so that said mandrel isaxially movable relative to said roll-cage, said mandrel, Whilerotating, being axially advanced by a measurable axial force withcooperating means to sense the increase in said axial force produced themoment several angularly spaced areas on the tube outer surface arebrought into firm contact with the defining wall of its tube-hole,whereupon said apparatus is thereafter controlled to produce apreselected, additional, axial advance of said rotating mandrel, wherebysaid tube portion is expanded to the preselected tightness in itstube-hole; wherein force-sensing means is provided for sensing themagnitude of said measurable axial force advancing said mandrel, so thatif the magnitude of said axial force increases to a preselectedmagnitude greater than the maximum magnitude normally produced duringthe expanding of a tube-portion, said force-sensing means is actuated toinitiate actions of the apparatus control system whereby theaxial-advancing is immediately stopped, said rotating mandrel isretracted, and means are actuated to make said control system inoperableand to indicate said axial force reached the preselected excessivemagnitude.

3. An apparatus which powers and controls a rollertype tube-expandingtool as it expands a lineal portion of a tube to a preselected tightnessin its tube-hole, said tool having a plurality of angularly-spaced,rotatable, radially movable, expanding rolls caged in anaxiallypositionable, rotatable, roll-cage mounted about a tapered,axially movable, rotatable, mandrel, with said ap paratus supportingsaid roll-cage assembly and said tapered mandrel so that said mandrel isaxially movable relative to said roll-cage, said mandrel, whilerotating, being axially advanced by a measurable axial force withcooperating means to sense the increase in said axial force produced themoment several angularly spaced areas on the tube outer surface arebrought into firm contact with the defining wall of its tube-hole,whereupon said apparatus is thereafter controlled to produce apreselected, additional, axial advance of said rotating mandrel, wherebysaid tube portion is expanded to the preselected tightness in itstube-hole; wherein force-sensitive means is provided for sensing themagnitude of said axial force advancing said mandrel during. saidpreselected, additional, axial advance of said mandrel, so that if themagnitude of said axial force during, and before the end of, saidpreselected, additional, axial advance does not equal, or exceed, themagnitude of said axial force at the moment the several angularly spacedareas on the tube outer surface are brought into firm contact with thedefining wall of the tube-hole, the apparatus control system is madeinoperable, and an indicator is actuated to thus indicate said axialforce did not increase to the preselected, minimum, magnitude before theend of said preselected, additional, axial advance of said mandrel.

4. An apparatus which powers and controls a rollertype tube-expandingtool as it expands a lineal portion of a tube to a preselected tightnessin its tube-hole, said tool having a plurality of angularly-spaced,rotatable, radially movable, expanding rolls caged in anaxiallypositionable, rotatable, roll cage mounted about a tapered,axially movable, rotatable, mandrel, with at least some of said rollscocked to effect a self-feeding of the mandrel, with said apparatussupporting said roll-cage assembly and said tapered mandrel so that saidmandrel is axially movable relative to said roll-cage, said mandrel,while rotating, being axially advanced by a measurable axial force withcooperating means to sense the increase in said axial force produced themoment several angularly spaced areas on the tube outer surface arebrought into firm contact with the defining wall of its tube-hole,whereupon said apparatus is thereafter controlled to produce apreselected, additional, axial advance of said rotating mandrel, wherebysaid tube portion is expanded to the preselected tightness in itstube-hole; wherein means is provided to stop the self-feeding elfectproduced by said cocked rolls at the moment the preselected, additional,axial advance of said mandrel starts, so that the only additional axialadvance of said mandrel, after the several angularly spaced areas on thetube outer surface are brought into firm contact with the defining wallof the tube-hole, is said additional axial advance produced by saidapparatus, said self-feeding action being stopped by an opposing forceacting to hold back the mandrel, with said opposing force being equalto, or greater than, the mandrel-advancing force produced by theself-feeding action of the tool.

5. In an automatic machine containing an apparatus which powers andcontrols a roller-type tube-expanding tool as it expands a linealportion of a tube to a preselected tightness in its tube-hole, said toolhaving a plurality of angularly-spaced, rotatable, radially movable,expanding rolls caged in an axially positionable, rotatable, roll-cagemounted about a tapered, axially movable, rotatable, mandrel, with saidapparatus supporting said roll-cage assembly and said tapered mandrel sothat said mandrel is axially movable relative to said roll-cage, saidmandrel, while rotating, being axially advanced by a measurable axialforce with cooperating means to sense the increase in said axial forceproduced the moment several angularly spaced areas on the tube outersurface are brought into firm contact with the defining wall of itstube-hole, whereupon said apparatus is thereafter controlled to producea preselected, additional, axial advance of said rotating mandrel,whereby said tube portion is expanded to the preselected tightness inits tube-hole; with said automatic machine carrying, at least, the tooldriver portion of said apparatus, so as to move said tool driver in twonormal directions over an area containing a quantity of said tube-holes,with said moves being programmed and controlled so as to position saidtool driver with the axis of its tube-expanding tool coinciding with theaxis of the selected tube-hole, so that said tool driver can then beaxially advanced to get its tube-expanding tool into the tube portionand to then expand said tube portion, with means whereby, after saidtool driver and its tube-expanding tool are retracted, said tool islubricated with a controlled amount of lubricant, before, or as, saidautomatic machine moves said tool driver and its tube-expanding tool tothe next programmed location.

6. An apparatus as in claim 1; including force-sensing means for sensingthe magnitude of said measurable axial force advancing said mandrel, sothat if the magnitude of said axial force increases to a preselectedmagnitude greater than the maximum magnitude normally produced duringthe expanding of a tube-portion, said force-sensing means is actuated toinitiate actions of the apparatus control system whereby theaxial-advancing is immediately stopped, said rotating mandrel isretracted, and means are actuated to make said control system inoperableand to indicate said axial force reached the preselected excessivemagnitude.

7. An apparatus as in claim 3; including force-sensing means for sensingthe magnitude of said measurable axial force advancing said mandrel, sothat if the magnitude of said axial force increases to a preselectedmagnitude greater than the maximum magnitude normally produced duringthe expanding of a tube-portion, said forcesensing means is actuated toinitiate actions of the apparatus control system whereby theaxial-advancing is immediately stopped, said rotating mandrel isretracted, and means are actuated to make said control system inoperableand to indicate said axial force reached the preselected excessivemagnitude.

8. An apparatus as in claim 1; wherein said axial movemerits of saidmandrel are produced by an hydraulic cylinder-and-piston motor containedin the tool driving portion of said apparatus.

9. An apparatus as in claim 2; wherein said axial movements of saidmandrel are produced by an hydraulic cylinder-and-piston motor containedin the tool driving portion of said apparatus.

10. An apparatus as'in claim 3; wherein said axial movements of saidmandrel are produced by an hydraulic cylinder-and-piston motor containedin the tool driving portion of said apparatus.

11. An apparatus as in claim 4; wherein said axial movements of saidmandrel are produced by an hydraulic cylinder-and-piston motor containedin the tool driving portion of said apparatus.

References Cited UNITED STATES PATENTS 9/1954 Stary 7 220 3/1956 Mathews29157.5

THOMAS H. EAG-ER, Primary Examiner US. Cl. X.R.

i T? 7 V UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PatentNo. 3 1 585 701 Dated June 22 1 971 Inventor(s) Walter E Stary It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 1, line 32, cancel "con- Column 3, line 30, "3, as" should read3. As Column 4, line 38, "contact PS" should read contact PX line 51,"T4," should read T4. Column 6, line 17, after "becomes" insert tightline 20, "momen" should read moment Column 8, line 55, "valve A" shouldread valve Al Column 10, lines 24 thru 29 should read MCZ acts FIG. 14has means for sensing the actuating of pressure-sensitive unit PXZ twiceduring a normal tube-expanding cycle together with means whereby thesecond acting of said pressure-sensitive unit PXZ inspects the qualityof the tube-joint being made. The actions of the FIGS. 13 and 14 systemsin powering, controlling, and Column 11, line 39, "cross' should readacross Signed and sealed this 16th day of May 1972.

(SEAL) Attest:

EDWARD M. FLETCHER ,JR ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents FORM PC4050 USCOMM-DC BOBIG-PGQ I! U 5 GOVERNMENT PRINTINGOFFICE. I959 O-JQllll

